A stroller mainly aims to carry and transport an infant or smaller child outdoors. It usually has to be folded and shrunk to a smaller size for transportation and storage. To meet this purpose many types of folding structure have been developed. Most of them require users to do extension and folding with two hands, but cannot be folded and extended singlehanded. While they usually provide a frame with a plurality of hinged joints to facilitate folding and shrinking, they mostly do not have desired stability and strong enough joints during extended condition, especially on the handlebar portion. Falling apart of elements could happen.
Moreover, when moving the front wheels of the stroller straight ahead without turning to the left or right side is desired, the wheels have to be set in a forward moving state. Adjustment of direction setting for the wheels is difficult. In the event that the two front wheels are not being set in a uniform direction the stroller tends to be bumpy during moving and require a lot of efforts to move and maneuver. The infant or child sitting inside could be jolted and feel uncomfortable.